The invention relates to a device for receiving and transporting molded parts made in cavities, in particular plastic molded parts, through a production line (processing line) with several work stations. Preferred field of application of the invention is the production of high-quality, flat plastic parts, in particular the production of plastic panes.
It is known from the prior art to use a so-called index plate for producing molded parts with several components in a work station of a machine for processing plastic material, whereby the index plate is used to transfer the molded parts between the individual cycles within this work station. The index plate is configured as transfer frame and includes retaining elements on which the molded part is initially formed on and transferred therewith. Removal of the molded parts is realized by moving the retaining elements away from the molded part which is then withdrawn by a separate handling system or falls out of the work station. In a two-cycle machine, the index plate turns from the first cycle to the second cycle by 180xc2x0, at several cycles with respectively shorter turns. In any event, the index plate with its retaining elements remains in this work station.
The invention is now based on the object to provide a device by which molded parts, in particular plastic molded parts, made in cavities, can be removed from the cavities and transported through several work stations.
According to one aspect of the invention, the molded parts can travel through a production line with several work stations, without requiring contact with the molded part itself. This is especially of importance when manufacturing high-quality plastic panes because any adverse effect in quality or damage to the surface can be eliminated, when avoiding a contact therewith. In accordance with the invention, it is hereby proposed to use a transfer frame which travels through the production line and includes retaining elements on which the molded part in the cavity is formed. The transfer frame is then removed together with the molded part from the respective work station and can be further transported along the processing line. Hereby, it is necessary to provide the molds in the area of the retaining elements with recesses in correspondence to the contour of the retaining elements, so that the latter closely abut in a form-fitting manner the mating surfaces of the mold halves, when the mold is closed. Care should be taken that the retaining elements so project into the space between the mating surfaces as to realize a bond with the molded parts during production of the molded parts.
According to one embodiment of the invention, linear guides with respective guide rails may be provided for the transport of the transfer frame through the processing line. The transfer frames may be transported through the processing line on the guide rails in upright disposition or suspended disposition. As an alternative, the embodiments provide for gripper arms having grippers for moving the transfer frames.
The manufacture of flat plastic parts by means of an injection compression process with dipping peripheral dies requires measures to detach the molded parts from the fixed or the moving mold half. Accordingly, the linear guide in the area of the mold halves includes segments which are movable orthogonal to the partition plane of the mold halves. The segments may be configured, for example, as a compound table. For implementing a smoothest possible run of the transfer frame on the linear guide, the linear guide is implemented as ball-type linear guide.
The use of the invention for the preferred field of application requires the provision of retaining elements which can be attached to the edge of the pane and easily separated therefrom again. The retaining elements may have particularly configured pointed ends for engagement into the edge of the pane. In order to be movable away from the panes, the retaining elements are slidingly supported in the transfer frame and can be displaced therein by suitable means.
According to another aspect of the invention, transfer frames and retaining elements can be completely eliminated. Rather, a linear transport system, for example a transport rope, is used for receiving as well as transporting the molded parts. The transport rope thus assumes a dual function and replaces the transfer frame and the retaining elements. In this case, the transport system engages directly into the cavities, and the molds are provided in the area of the linear transport systems with recesses in correspondence to the cross section of the linear transport systems, so that the latter effect a form-fitting seal with the mating surfaces of the mold halves, when the mold is closed. According to a particularly advantageous embodiment, a rope is used which is embraced by the molded part, when being formed thereon, only to such an extent that its cross section is not completely embraced. The molded part can then easily be pushed off the rope. The use in the injection compression process, i.e. when using dipping peripheral dies, it is advantageous to provide one or more stroke elements by which the linear transport systems can be moved orthogonal to the transport direction in order to detach the molded parts from the fixed or the moving mold half.
The present invention is suitable for single component injection as well as, in particular, for multi-component injection of plastic molded parts. The invention is usable in horizontal as well as vertical injection molding machines or injection compression machines. Especially suitable is the invention for the production of also large-area, flat plastic parts with extreme, optical surface properties. Moreover, the invention permits the use of a small mold opening space which can be kept more easily under clean air conditions. Therefore, it is possible to easily operate at clean air conditions. Furthermore, the invention provides for a high degree of freedom with respect to the constructive configuration of the plastic parts because random components can be attached by injection onto the main plastic part, either completely or partially and one-sided or two-sided, or fully one-sided (overlay). Moreover, the device according to the invention permits the use of short cycles.